Slurry composition, method of polishing an object and method of forming a contact in a semiconductor device using the slurry composition

Abstract

In a slurry composition preventing damage to an insulation layer, and uniformly polishing a metal layer, the slurry composition includes an acidic aqueous solution having a first pH and an anionic surfactant having a second pH lower than or equal to the first pH. Irregular polishing of the metal layer relative to a pattern density may be prevented and a contact having a uniform thickness may be formed using the slurry composition.

1 . A slurry composition comprising: 
 an acidic aqueous solution having a first pH; and    an anionic surfactant having a second pH lower than or equal to the first pH.    
   
   
       2 . The slurry composition of  claim 1 , wherein the anionic surfactant comprises at least one of a phosphoric acid compound, a phosphate compound, a sulfonic acid compound, a sulfonate compound, a carboxylic acid compound, a carboxylate compound, an acrylic acid compound and an acrylate compound.  
   
   
       3 . The slurry composition of  claim 2 , wherein the anionic surfactant comprises said phosphate compound.  
   
   
       4 . The slurry composition of  claim 3 , wherein the phosphate compound comprises a polyoxyalkylene alkyl aryl phosphate compound.  
   
   
       5 . The slurry composition of  claim 1 , wherein the anionic surfactant comprises an oxyalkylene chain.  
   
   
       6 . The slurry composition of  claim 5 , wherein the oxyalkylene chain is selected from the group consisting of oxymethylene chain, oxyethylene chain, oxypropylene chain and oxybutylene chain.  
   
   
       7 . The slurry composition of  claim 5 , wherein the oxyalkylene chain has a number of oxyalkylene repeating units of from about 20 up to about 60.  
   
   
       8 . The slurry composition of  claim 1 , wherein the anionic surfactant comprises an alkyl chain having from 1 up to 40 carbon atoms.  
   
   
       9 . The slurry composition of  claim 8 , wherein the alkyl chain has from 1 up to 20 carbon atoms.  
   
   
       10 . The slurry composition of  claim 1 , wherein the first pH is from about 1 up to about 6.  
   
   
       11 . The slurry composition of  claim 1 , wherein the second pH is from about 1 up to about 5.  
   
   
       12 . The slurry composition of  claim 1 , wherein the acidic aqueous solution comprises an oxidizing agent, an abrasive and water.  
   
   
       13 . The slurry composition of  claim 12 , wherein the oxidizing agent comprises a peroxide compound, a ferric compound, or a mixture thereof.  
   
   
       14 . The slurry composition of  claim 13 , wherein the peroxide compound comprises at least one of hydrogen peroxide, benzoyl peroxide, calcium peroxide, barium peroxide and sodium peroxide.  
   
   
       15 . The slurry composition of  claim 13 , wherein the ferric compound comprises at least one of ferric nitrate, potassium ferricyanide, ferric phosphate and ferric sulfate.  
   
   
       16 . The slurry composition of  claim 12 , wherein the abrasive comprises at least one of silica, alumina, ceria, zirconia and titania.  
   
   
       17 . The slurry composition of  claim 1 , further comprising a pH-controlling agent.  
   
   
       18 . The slurry composition of  claim 17 , wherein the pH-controlling agent comprises at least one base of potassium hydroxide, ammonium hydroxide, sodium hydroxide, tetramethylammonium hydroxide and choline, or at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid and acetic acid.  
   
   
       19 . The slurry composition of  claim 1 , wherein the slurry composition comprises from about 0.001 up to about 10 parts by weight of the anionic surfactant, based on about 1,000 parts by weight of the slurry composition.  
   
   
       20 . The slurry composition of  claim 19 , wherein the slurry composition comprises from about 0.01 up to about 5 parts by weight of the anionic surfactant, based on about 1,000 parts by weight of the slurry composition.  
   
   
       21 . A slurry composition comprising: 
 an acidic aqueous solution including an oxidizing agent, an abrasive and water, the acidic aqueous solution having a first pH; and    an anionic surfactant having a second pH lower than or equal to the first pH.    
   
   
       22 . The slurry composition of  claim 21 , further comprising a pH-controlling agent.  
   
   
       23 . A method of polishing an object comprising: 
 preparing an object;    introducing a slurry composition to a polishing pad, the slurry composition including an acidic aqueous solution having a first pH and an anionic surfactant having a second pH lower than or equal to the first pH; and    polishing a surface of the object by contacting the polishing pad and the surface of the object.    
   
   
       24 . The method of  claim 23 , wherein preparing the object further comprises: 
 forming an insulation layer on a substrate, the insulation layer including an opening; and    forming a metal layer on the insulation layer to fill the opening.    
   
   
       25 . The method of  claim 24 , wherein polishing the surface of the object is performed until an upper surface of the insulation layer is exposed.  
   
   
       26 . The method of  claim 24 , wherein the insulation layer comprises an oxide.  
   
   
       27 . The method of  claim 24 , wherein the metal layer comprises tungsten.  
   
   
       28 . The method of  claim 27 , wherein the first pH is from about 1 up to about 5.  
   
   
       29 . The method of  claim 27 , wherein the second pH is from about 1 up to about 4.  
   
   
       30 . The method of  claim 24 , wherein the metal layer comprises aluminum or copper.  
   
   
       31 . The method of  claim 30 , wherein the first pH is from about 2 up to about 6.  
   
   
       32 . The method of  claim 30 , wherein the second pH is from about 2 up to about 5.  
   
   
       33 . A method of forming a contact in a semiconductor device comprises: 
 providing a substrate;    forming an insulation layer on said substrate, said substrate including a lower structure;    partially removing the insulation layer to form a contact hole exposing a portion of the lower structure;    forming a conductive layer on the insulation layer which fills the contact hole; and    chemically and mechanically polishing the conductive layer with a slurry composition including an acidic aqueous solution having a first pH, and an anionic surfactant having a second pH lower than or equal to the first pH, until an upper surface of the insulation layer is exposed.    
   
   
       34 . The method of  claim 33 , wherein the insulation layer comprises an oxide.  
   
   
       35 . The method of  claim 33 , wherein the conductive layer comprises at least one of tungsten, aluminum and copper.